Myths tested:Are electric cars slower than gas-powered ones?Do greenhouse gases increase the amount of heat absorbed by air?Do cows hurt the environment?Can cow manure be used to help the environment?Note: This episode aired on the Science Channel. Former MythBuster Scottie Chapman reappeared in this episode to assist in the testing, along with Discovery Channel's young scientist winners.

During 2010, Discovery Channel aired a series of episodes that were titled "Buster's Cut". According to the episode introductions, these were edited reruns of earlier episodes featuring never before seen footage and behind the scenes information.

They first had Jamie drive Brandon (a Young Scientist Challenge winner) in both a gas and electric consumer grade car, and blindfolded Brandon and covered Jamie's ears to see if they could tell the difference. Brandon couldn't tell, but being an experienced driver, Jamie was able to immediately tell based on the electric car's acceleration. Then, Adam, Jamie, and Brandon built an electric go-kart using lithium iron phosphate batteries and tested it against a gas go-kart. Despite weighing twice as much as the gas go-kart, the electric go-kart performed about the same. Then they went to a professional track and watched the KillaCycle, an electric drag motorcycle race against a stock gas motorcycle. The gas motorcycle won by a slight margin. Then they had the X1 electric sports car race against a Ferrari F430, and while the Ferrari's top speed was faster, the electric car accelerated faster and beat it in a drag race. Finally, they had the electric car race against an FJR50 Formula 3 race car. While the Formula 3 car easily beat the electric car, the electric car is considered a "street car", not a race car, and it did well enough that they proclaimed electric cars to be anything but slow.

Cows emit methane—though not mostly from flatulence, but from belching — and their feces emit even more methane once they begin rotting. Since there are so many cows, the methane contributes significantly to global warming.

Cow manure can be used to help the environment.

Confirmed

Cow manure can be used to power things. The Young Scientists helped collect cow manure and extracted methane gas from it. Grant hooked up the methane gas and used it to power a hand lawnmower. They then saw that the farm where they had collected cow manure from received 90% of its electricity from its own manure-powered generator.